The present invention is a thread bobbin that can automatically rewind a predetermined length of thread but will permit any length of thread to be manually rewound. The bobbin is particularly useful for tying artifical flies for fishing lures.
Fly tying is a hobby for many fishermen that is second in enjoyment only to actually being out on a lake or stream. For others it is a means of earning a livelihood by tying flies professionally. Increasingly sophisticated equipment has become available over the years to enable flies of higher quality to be tied with greater ease. Much of this effort has gone into the design of better vises that hold the hook while the dressing is being applied. Surprisingly, relatively little thought seems to have gone into improving devices that hold the thread that much be applied to hold the dressing in place. Until recently, thread bobbins have been little more than crude handles on which a spool of thread is mounted.
Some attempts have been made in the past to develop improved bobbins. Among these can be mentioned U.S. Pat. Nos. 2,220,878 to Harvey and 2,338,353 to Perkins. Both of these are simple devices that do little more than guide the thread off the roll to the point of use. More recently Bloch, in U.S. Pat. No. 4,462,551, described a thread bobbin that was a major improvement over these eariler devices. The Bloch bobbin enabled a length of thread to be withdrawn and tied onto the fly. The bobbin could then hang freely by the thread without unwinding any further. When the fly was completed a given length of thread could be rewound automatically simply by lifting the bobbin to take the tension off the thread. However, the Bloch devices has the deficiency that any excess thread beyond that given length could not be rewound at all. The bobbin contains an internal spring that limited rewinding to only the predetermined length. This was both an inconvenience and a waste since any excess thread would often have to be clipped off and discarded.
Clutches operating against thread spools are known from the sewing and weaving arts. One example is shown in U.S. Pat. No. 460,723 to Eisenhart. However, devices of this type have little usefulness for the professional or recreational fly tier.